The phenotype of SLE associated with complete deficiency of complement isotype C4A.
Complete deficiency of the complement C4A isotype is a known genetic risk factor for systemic lupus erythematosus (SLE). The disease phenotype of C4A-deficient patients has never been defined. Among 200 patients with SLE from five centers, 18 (9%) with C4A deficiency were identified. These individuals were compared to those who were C4A replete with regard to a series of clinical and serologic features. The only significant differences between the two groups were in the presence of renal disease (C4A deficient, 11%; C4A replete, 46%; P < 0.006) and a decrease in the serum concentrations of C3 (C4A deficient, 11%; C4A replete, 35%; P < 0.04). There was also a trend for the C4A-deficient individuals to have milder disease. In light of the tendency for C4A-deficient individuals to have lower serum concentrations of C4, it is important that such patients not be subjected to overly aggressive efforts to "normalize" their C4 levels.
Welch
T R
TR
Division of Nephrology, Children's Hospital Research Foundation, Cincinnati, Ohio 45229-3039, USA.
Brickman
C
C
Bishof
N
N
Maringhini
S
S
Rutkowski
M
M
Frenzke
M
M
Kantor
N
N
D000328:Adult; D000483:Alleles; D044383:Black People / Q000235:genetics; D003176:Complement C3 / Q000032:analysis; D015934:Complement C4a / Q000032:analysis / Q000172:deficiency*; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D015337:Multicenter Studies as Topic; D010641:Phenotype; D012720:Severity of Illness Index; D044465:White People / Q000235:genetics
D003176:Complement C3; D015934:Complement C4a